Great question. I'm afraid I'll have to watch all three episodes again, back to back this time. I hope you don't mind me putting the names of the villains in a spoiler tag though.
– Mr ListerDec 7 '15 at 9:11

3 Answers
3

I'm pretty sure that you're correct, Ashildr was given the power of the Quantum Shade in exchange for securing The Doctor in the teleport bracelet on behalf of

The Time Lords.

However, I was under the impression that the Quantum Shade was an independent being, with whom Ashildr negotiated her own deal.

This deal was that the Quantum Shade would perform the execution for her after an allotted time has elapsed, and in return is allowed to claim the soul of the victim. AFAIK this is the deal that was made for any execution that was dealt.

Ashildr has the power to renegotiate that deal at any point, which was her plan with Rigsy. She never intended to kill him, she just wanted to have a countdown so that The Doctor would have a time limit to solve the puzzle that she had laid out for him. This is why she staged the elaborate framing of the murder on Rigsy.

However, when Clara accepts the Quantum Lock from Rigsy, she is essentially renegotiating the deal with the Shade. The soul that was promised is now Clara's instead of Rigsy's, and Ashildr has no say in that transaction. Therefore she has no way of rescinding the deal with the Shade.

Almost certainly yes.

DOCTOR: It's called a Quantum Shade. It's kind of a spirit. Once it's bound to a victim ... you could flee across all of time and all of the universe, it would still find you.

A creature that can lock on to a signal and follow it across all of time and space? Who does that remind you of? That's right, the Time Lords. They have more advanced abilities in travel through time and space than any other civilisation we know of. It sounds as though the Quantum Shade may have some of the abilities of a TARDIS.

The fact that the Doctor has such familiarity with the idea of a Quantum Shade could also be seen as suspicious ... or maybe not, since he knows an awful lot about all sorts of creatures.

Finally, again from the transcript:

ASHILDR: I made a deal to protect the street. They take you, I take the key so you can't be traced. I do as they tell me, and the street is safe.

What did the Time Lords give her in exchange for her capture of the Doctor? It must have been something that enabled her "to protect the street". And what does she use to preserve the peace on the street, other than the Quantum Shade?

So it looks like yes, the Time Lords supplied Ashildr with the Quantum Shade.

To begin with, the episode Face the Raven leaves implied that the Quantum Shade has been present since the inception of the Trap Street, otherwise there would be no way to ensure cooperation of the very dangerous alien individuals taking refuge there. Second, it acts like an independent being, as @Mike.C.Ford mentioned. Third, in the episode it seemed to me that the deal to protect the street is rather a threat by

the Time Lords

that they'd intervene unless Ashildr did as they wanted. There's nothing saying they can't run a protection racket, after all.